The present invention relates to a data processing apparatus and in particular relates to a data processing apparatus having a function responsive to an interruption request. An example of such a data processing apparatus comprises a printer controller for controlling a printer coupled to a plurality of host systems.
Network systems such as a so-called UNIX (a multiuser, multitasking operating system for use on minicomputers) have been recently developed. Such development of network systems enables that any of a plurality of users may use an arbitrary printer. In such an environment, a possibility of flexible management of a relevant network is remarked. It is expected that such flexible management achieves smooth and optimum printing-out works (for making relevant documents) being carried out by users. Such flexible management may be achieved by bi-directional communication between a printer and a host such as a printer server.
A printer controller according to related art will now be described. This printer controller is used so as to control a printer coupled to a plurality of host systems. There may be a case where these respective host systems give a plurality of jobs (for printing out corresponding documents) to this printer at a time. In such a case, the printer controller makes the printer carry out a job which was given first, the printer thus printing out a document associated with this job. The remaining jobs among the at-a-time-given plurality of jobs are registered onto a list according to a sequence in which the jobs were given. Then, the printer controller makes the printer carry out these jobs according to the sequence in which the jobs were registered in the list (a first-in-first out (FIFO) queue).
There is a problem in such a manner as mentioned above, in which manner a plurality of jobs are handled by the printer controller according to the related art. The problem occurs in a special case where a printing-out work is requested urgently or another special case where only one page is requested to be printed out. In such special cases, these requests are handled similarly to other printing out requests. Thus, these requests associated with such special cases are first registered in the list and then it is to be awaited for their turns to come round. Alternatively, a user who intends to carry out one of these special jobs should ask another user whose job is currently being dealt with to stop dealing with the job so that the user intending to carry out the special job may be allowed to carry out his or her job. Such a way as asking the other user is a troublesome problem.